@madduci
Well, since you're running jessie my advice is to simply install QtCreator from the distribution repository. You can then use it to develop with whichever version of Qt you want.

The distribution also provides Qt 5.3.2 if you want to make use of it (a bit outdated, but stable), which'd be a good choice unless you want to specifically employ something from Qt 5.6 (like a fixed bug or a new feature).